1. Field of the Invention
The present invention relates to aqueous alkyldiketene dispersions comprising an alkyldiketene, cationic starch and anionic dispersants, and to the use of the aqueous alkyldiketene dispersions as body size in the manufacture of paper, paperboard and cardboard and also for making cellulose fibers hydrophobic.
2. Description of the Background
EP-B-0 353 212 discloses sizes in the form of aqueous emulsions comprising a hydrophobic cellulose-reactive size, e.g. fatty alkyldiketene, and a cationic starch having an amylopectin content of at least 85% and a degree of cationization (D.S.) of from 0.045 to 0.4. The proportion of amylopectin in the cationic starch is preferably from 98 to 100%.
EP-B-0 369 328 discloses aqueous alkyldiketene dispersions containing up to 30% by weight of ketenedimer. Further essential constituents of these alkyldiketene dispersions are cationic starch, preferably cationic waxy maize starch, aluminum sulfate, carboxylic acids having from 1 to 10 carbon atoms, and sulfonates such as the sodium salt of ligninsulfonic acid or condensation products of formaldehyde and naphthalenesulfonic acids.
EP-B-0 437 764 discloses stabilized aqueous alkyldiketene dispersions comprising, apart from an alkyldiketene, a protective colloid and an ester of a long-chain carboxylic acid and a long-chain alcohol. Preferred protective colloids are cationic starches. In addition, sorbitan esters, soaps, synthetic detergents and thickeners such as polymers of acrylamide, vinylpyrrolidone and N-vinyl-2-methylimidazoline can also be used.